The 26-year-old will spend the season at St James' Park having left Queens Park Rangers just seven months after joining them from Marseille.
"I'm very happy to be a Newcastle player. It will be a huge honour to play for such a big club. I was very flattered by the club's interest in me back in January and also very happy that they showed interest in me again this summer," Remy told the club's official website.
"The Premier League is the best league in the world and that's where I want to play. I am very motivated this year to get into the World Cup squad for my country. I know in order to do that I need to have a big season and a successful campaign with Newcastle United.
"I am focused on helping the team achieve success this season and scoring as many goals as I can."
Remy, who scored six goals in 14 appearances for QPR, has won 18 caps for France since his debut in 2007.